Clear cell tumour of the lung is a rare benign pulmonary neoplasm that contains an abundant amount of glycogen. It is often classified under the spectrum of perivascular epithelioid cell tumours (PEComas).
Usually seen as a rounded, smooth-walled, and peripheral parenchym...
Coal workers' pneumoconiosis (CWP) is an occupational disease (type of pneumoconiosis) caused by exposure to coal dust free of silica (washed coal). Histologically, CWP is classified according to disease severity into simple (presence of coal macules) and complicated (with progressive massive fi...
Coarctation of the aorta (CoA) refers to a narrowing of the aortic lumen. It can be primarily divided into two types:
infantile (pre-ductal) form: is characterised by diffuse hypoplasia or narrowing of the aorta from just distal to the brachiocephalic artery to the level of ductus arteriosus, t...
Coccidioidomycosis refers to an infection caused by the dimorphic fungus Coccidioides spp, usually localised to the lungs. This disease is not to be confused with the similarly named paracoccidioidomycosis.
The most common forms of Coccidioides spp are Coccidioides immitis and Coc...
Coin lesion refers to a round or oval, well-circumscribed solitary pulmonary lesion. It is usually 1-5 cm in diameter and calcification may or may not be present 1,3. Typically, but not always, the patient is asymptomatic 1.
The differential diagnosis for such lesions i...
The collar sign, also called the hourglass sign, is a helpful sign for diagnosis of diaphragmatic rupture on coronal or sagittal CT/ MR images and barium studies. It refers to a waist-like or collar-like appearance of herniated organs at the level of the diaphragm.
dependent viscera s...
Combined pulmonary fibrosis and emphysema (CPFE) are a possible new addition to a growing list of smoking-related lung disease characterised by the coexistence of usual interstitial pneumonia (UIP) or nonspecific interstitial pneumonia (NSIP) with emphysema in smokers.
The comet tail sign is a finding that can be seen on CT scans of the chest. It consists of a curvilinear opacity that extends from a subpleural "mass" toward the ipsilateral hilum. The comet tail sign is produced by the distortion of vessels and bronchi that lead to an adjacent area of round ate...
Common variable immunodeficiency (CVID) is a condition that is associated with an impaired immune system. It is considered the most common symptomatic primary immunodeficiency, and is characterised by recurrent respiratory tract infections.
The commonest presentation is t...
Pulmonary manifestations of common variable immunodeficiency can be variable. The respiratory system is one of the most commenly affected systems in common variable immunodeficiency.
Radiographic disease spectrum
bronchiectasis with interstitial lung disease
could either be due to ...
Complete tracheal rings are a rare, isolated tracheal or tracheobronchial anomaly resulting from abnormal cartilage growth, forming a complete ring and often causing airway stenosis.
Clinically, it manifests as respiratory distress in infants or mild symptomatic airway co...
Computed tomography (CT) of the chest is a cross-sectional evaluation of the heart, airways, lungs, mediastinum, and associated bones and soft tissues.
Two key methods of image acquisition include:
standard CT with 5 mm slice thickness for mediastinum and gross evaluation of lungs
Mnemonics for conditions with a lower lobe predominance in chest radiology include:
C: collagen vascular disease
I: idiopathic pulmonary fibrosis
A: aspiration pneumonia
D: drugs; desquamative interstitial pneumonia
Congenital cardiovascular anomalies are relatively common, with an incidence of up to 1% if small muscular VSDs are included. As a group, there is a much greater frequency in syndromic infants and in those that are stillborn.
These defects as a group have a heterogeneous aetiology w...
Congenital cystic bronchiectasis is a rare entity, and as the name suggests is characterised by cystic bronchiectasis found in infancy 1. The term appears to have fallen out of favour, due to variable use in older literature. In most instances of congenital cystic bronchiectasis has what is now ...
With the advent of echocardiography, and cardiac CT and MRI, the role of chest radiographs in evaluating congenital heart disease has been largely been relegated to one of historical and academic interest, although they continue to crop up in radiology exams. In most instances a definite diagnos...
Congenital high airways obstruction syndrome (CHAOS) refers a rare, often lethal, congenital laryngotracheal condition and is primarily characterised by obstruction to the fetal upper airway.
CHAOS can be of three possible types 2:
complete laryngeal atresia without an oesophageal f...
Congenital lobar overinflation (CLO), previously called congenital lobar emphysema, is a congenital lung abnormality that results in progressive overinflation of one or more lobes of a neonate's lung.
On imaging, it classically presents on chest radiographs as a hyperlucent lung segment with o...
Congenital pulmonary airway malformations (CPAM) are multicystic masses of segmental lung tissue with abnormal bronchial proliferation. CPAMs are considered part of the spectrum of bronchopulmonary foregut malformations.
Until recently they were described as congenital cystic adeno...
Congenital pulmonary lymphangiectasia refers to congential dilatation of the lymphatic system.
It typically presents in infancy. It may be isolated to lung or may be part of a generalised lymphangiectasia.
Congenital pulmonary venolobar syndrome is a condition comprised of a rare group of cardiac and pulmonary congenital abnormalities occurring variably in combination. The abnormalities include:
anomalous pulmonary venous drainage
particularly scimitar syndrome with hypogenic right lung
Congenital tracheomalacia refers to a diverse group of conditions which result in a dilated trachea with increased compliance. Causes include:
cystic fibrosis: seen in up to 69% of patients 4
Mounier-Kuhn syndrome: idiopathic or associated with
Ehlers-Danlos syndrome (in adults)
cutis laxa (...
Congenital tracheo-oesophageal fistula is a congenital pathological communication between the trachea and oesophagus.
Tracheo-oesophageal fistula and oesophageal atresia have a combined incidence of approximately 1 in 3500 live births 1-3,5. There is only a minimal hereditary/ge...
Congestive cardiac failure (CCF), also known as congestive heart failure (CHF), refers to the clinical syndrome caused by inherited or acquired abnormalities of heart structure and function, causing a constellation of symptoms and signs that lead to decreased quality and quantity of life.
Constrictive pericarditis (or perhaps better termed pericardial constriction) is a type of pericarditis which leads to diastolic dysfunction and potentially symptoms of right heart failure.
No single demographic is affected as there are numerous causes of constrictive pericarditi...
The continuous diaphragm sign is a chest radiograph sign of pneumomediastinum or pneumopericardium if lucency is above the diaphragm, or of pneumoperitoneum if lucency is below the diaphragm.
Normally the central portion of the diaphragm is not discretely visualised on chest radiographs as it ...
COPD (chronic obstructive pulmonary disease) is defined as a condition characterised by persistent air flow limitation that is usually progressive and associated with an enhanced chronic inflammatory response in the airways and the lung to noxious particles or gases 1.
The coracoclavicular joint is a normal variant of the pectoral girdle, where the conoid tubercle of the clavicle appears enlarged or elongated, with a flattened inferior surface where it approximates the coracoid process of the scapula to form an articulation.
More common in Asia...
Correct chest radiograph terminology is very helpful when describing pathology. It is especially important when describing findings to colleagues (radiologist or not) or when describing a film in a radiology exam.
Terms to avoid
There are some terms that will drive people wild! Steer clear o...
The costal cartilages form part of the thoracic cage and anterior chest wall. There are 10 costal cartilages, one for rib 1-10, with each of which forms a costochondral joint. Costal cartilages 1-7 articulate with the sternum at sternocostal joints, and costal cartilages 8-10 are attached to eac...
Costal cartilage fractures are fractures of the cartilage connecting the ribs anteriorly to the sternum.
There is little published data on costal cartilage fractures. Most reported cases are in males and resulted from blunt trauma or a fall 1-2.
In young ch...
The costocervical trunk is one of the branches of the second part of the subclavian artery. It arises from the posterior wall of the subclavian artery, posterior or medial to the anterior scalene muscle and courses posterosuperiorly across the suprapleural membrane where it divides into 2 branc...
The costochondral joints are the joints between each rib and its costal cartilage. They are primary cartilaginous joints. These joints represent the demarcation of the unossified and ossified part of the rib 1. The joint is held together by periosteum, with the lateral aspect of the costal ca...
The costoclavicular ligament or rhomboid ligament is the major stabilising factor of the sternoclavicular joint.
The costoclavicular ligament binds the inferior medial clavicle (via the rhomboid fossa) to the first costal cartilage and adjacent end of the first rib. It is compose...
The costoclavicular space is the anterior portion of the superior thoracic aperture, between the clavicle and first rib. The subclavian vessels and brachial plexus pass though the space related to the scalene muscles. Proximally, the plexus passes through the interscalene space, and distally thr...
The costovertebral joint is an articulation between the ribs and the vertebral column.
The ribs articulate with the thoracic vertebrae via two distinctly different joints:
costovertebral joint - articulation between the head of the rib and the vertebral body
Crack lung is a term used to describe one of the respiratory complications of smoked crack cocaine.
Patients present with sympathetic hyperactivity such as tachycardia, hypertension, dilated pupils, and chest pain, productive cough, dyspnoea, and hypoxaemia along with fev...
Crazy paving refers to the appearance of ground-glass opacity with superimposed interlobular septal thickening and intralobular reticular thickening, seen on chest HRCT. It is a non-specific finding that can be seen in a number of conditions.
Croup, also called acute laryngotracheobronchitis is due to viral infection of the upper airway by parainfluenza virus or respiratory syncytial virus (RSV).
On imaging, although not required for the diagnosis, it classically presents with a narrowing of the subglottic airway and ballooning of t...
Crow feet sign is a characteristic but uncommon feature seen in round atelectasis.
On CT, this is seen as linear bands radiating from a mass into adjacent lung tissue resembling the feet of a crow. This sign should not be confused with fibrotic changes occurring in the lung.
Cryptococcosis is a fungal infection caused by Cryptococcus neoformans, a globally distributed fungus that is commonly found in soil, especially that containing pigeon and avian droppings. Infection is acquired by inhaling spores of fungus.
Occurs worldwide without any defined en...
Cryptogenic fibrosing alveolitis (CFA) is a fibrosing lung disease that is characterised by inflammation and fibrosis of the alveoli and interstitium of the lungs, favouring the subpleural and basal regions.
There is some overlap in definition with the term idiopathic pulmonary fibrosis 1.
Cryptogenic organising pneumonia (COP) is a disease of unknown aetiology characterised on imaging by multifocal ground glass opacifications and/or consolidation. A wide variety of infectious as well as noninfectious causes may result in a similar histologic pattern.
The CT angiogram sign refers to vessels appearing prominent during a contrast enhanced CT as they traverse an airless low attenuation portion of consolidated lung. Although initially thought to be specific for bronchoalveolar carcinoma, it has now been recognised as a generic appearance provided...
Chest CT is a computed tomography examination of the thoracic cavity performed for a variety of reasons, from suspected cancer to penetrating chest trauma.
A CT chest can be performed with or without IV contrast and when IV contrast is given, the timing of the contrast delivery can make a massi...
CT guided thoracic biopsy is usually performed for the diagnosis of suspicious lung, pleural or mediastinal lesions. It can be performed as an outpatient where patient monitoring and complications support are available.
pulmonary lesion inaccessible to bronchoscopy, or in which pri...
CT polytrauma/multitrauma (also called trauma CT) is an increasingly used test in the patient with multiple injuries sustained after significant trauma.
There is some evidence that trauma patients who undergo whole body CT (WBCT) / panscan have better survival than patients who undergo selectiv...
Chest x-ray CVC (central venous catheter) position should be assessed following initial placement and on subsequent radiographs.
This is a summary article; we do not have a more in-depth reference article.
may be inserted via
internal jugular vein (left ...
A number of entities can present as cyanotic congenital heart disease. These can be divided into those with increased or decreased pulmonary vascularity (pulmonary plethora):
increased pulmonary vascularity
total anomalous pulmonary venous return (TAPVR) (types I and II)
transposition of the ...
A cyst is an abnormal fluid filled structure which is lined by epithelium. This distinguishes it from a pseudocyst with lacks an epithelial lining and instead has a vascular and fibrotic capsule
Cysts are extremely common and found in many organs. Examples include:
Cystic bronchiectasis is one of the less common morphological forms of bronchiectasis. It is characterised by saccular dilatation of bronchi that extend to the pleural surfaces. When aggregated these may give a "bunch of grapes" like appearance. It may be present on its own or may be occur in co...
Cystic fibrosis (CF) is an autosomal recessive genetic disease that affects the exocrine function of the lungs, liver, pancreas and small bowel resulting in progressive disability and multi-system failure. This article is a general discussion of the disease. Each organ system will be discussed s...
Pulmonary manifestations of cystic fibrosis are some of the best known in cystic fibrosis (CF). This is partly because the lungs are often severely affected and the cause of significant morbidity and mortality.
For general discussion of cystic fibrosis, and a discussion of its other manifestat...
Cystic fibrosis transmembrane regulator (CFTR) is a protein encoded by the CFTR gene on chromosome 7q31.2 and is responsible for regulating chloride passage across cell membranes. It is this gene that is mutated in patients with cystic fibrosis (CF) resulting in abnormally thick secretions. Ther...
Cystic hygroma, also known as cystic or nuchal lymphangioma, refers to the cystic variety of congenital lymphangioma which, most commonly, occur in the cervicofacial regions, particularly at the posterior cervical triangle.
They usually occur in the fetal/infantile and paediatri...
Cystic lung disease can occur in a number pathological conditions.
A lung cyst is an air filled structure with perceptible wall typically 1 mm in thickness but can be up to 4 mm. The diameter of a lung cyst is usually <1 cm. By definition lung cyst can be distinguished from cavity ...
The gamut for cystic lung disease is long, but includes:
pulmonary Langerhans cell histiocytosis
lymphoid interstitial pneumonia
cystic lung disease
Cystic lesions in paediatric patients are usually congenital lesions and, as such, can be seen prenatally and following delivery.
These congenital lesions are predominantly covered by the overarching diagnosis of bronchopulmonary foregut malformation. This is a heterogeneous...
The differential diagnosis for cystic masses of the mediastinum include:
oesophageal duplication cyst
cystic degeneration of an intrathoracic tumour
mediastinal thoracic duct cyst
Cystic or necrotic appearing lymph nodes can be caused by a number of infectious, inflammatory or malignant conditions:
squamous cell carcinoma metastases
plasmacytoid T-cell leukemia
acute myeloid leukemia
herpes simplex lymphadenit...
Cystic pulmonary metastases are atypical morphological form on pulmonary metastases where lesions manifest as distinct cystic lesions. It is slightly different form the term cavitating pulmonary metastases in that the lesions are extremely thin walled.
It has been reported with many ...
A cystic retroperitoneal lesion can carry a relatively broad differenital which includes:
retroperitoneal cystic lymphangioma
retroperitoneal mucinous cystadenoma
retroperitoneal cystic teratoma
retroperitoenal cystic mesothelioma
pseudomyxoma retroperitonei with cystic change
Cytomegalovirus (CMV) pneumonia is a type of viral pneumonitis and occurs due infection with cytomegalovirus (CMV), which is a member of the Herpetoviridae family.
CMV infection is particularly important in those who are immunocompromised (e.g. those with AIDS / allogenic bone mar...
The dark bronchus sign is the appearance of a relatively darker bronchus as compared to adjacent ground glass opacity. If the ground glass opacity progresses to consolidation, air bronchograms will be visualised.
This sign is useful to identify diffuse ground glass opacity on HRCT chest in cas...
Along with the Stanford classification, the DeBakey classification is used to separate aortic dissections into those that need surgical repair, and those that usually require only medical management.
The DeBakey classification divides dissections into 1-5:
type I: involves asce...
A mnemonic used to remember the DeBakey classification 1 is:
B: both ascending and descending aorta (type I)
A: ascending aorta(type II)
D: descending aorta (type III)
The deep sulcus sign on a supine chest radiograph raises suspicion of a pneumothorax.
On a supine plain chest film (common in intensive care units or as part of a trauma radiograph series), it may be the only suggestion of a pneumothorax because air collects anteriorly and basally, within the n...
Dehiscence is a general term referring to 'splitting open' and is used in a variety of contexts in medicine generally and radiology more specifically.
The two most common usages are:
splitting open of a wound (e.g. sternal dehiscence)
loss of bone separating one structure from another (e.g. ...
The dense hilum sign suggests a pathological process at the hilum or in the lung anterior or posterior to the hilum. Malignancy, especially lung cancer, should be suspected.
On a well-centred chest posteroanterior (PA) radiograph the density of the hilum is comparable on ...
The dependent viscera sign is one of the signs of diaphragmatic rupture on axial CT or MR images, where herniated viscera lie against the posterior thoracic wall in a dependent position, as they are no longer supported by the diaphragm.
collar sign (or hourglass sign)
Desquamative interstitial pneumonia (DIP) is an interstitial pneumonia closely related to, and thought to represent the end stage of respiratory bronchiolitis interstitial lung disease (RB-ILD) 1. It is associated with heavy smoking.
It is considered one of the rarest of idiopathi...
Dextrocardia is a congenital cardiac malrotation in which the heart is situated on the right side of the body (dextroversion) with the apex pointing to the right.
Dextrocardia is believed to occur in approximately 1 in 12,000 people 2.
There are two main types of dextr...
The diaphragm is the dome-shaped muscle that separates the thoracic cavity from the abdominal cavity, enclosing the inferior thoracic aperture.
The muscular fibres of the diaphragm originate around the circumference of the inferior thorax and converge to a common insertion point ...
The diaphragmatic apertures are a series of apertures that permit the passage of structures between the thoracic and abdominal cavities. There are three main apertures:
aortic hiatus (T12) (not a true aperture)
oesophageal hiatus (T10)
vena caval foramen (T8)
The vertebral levels of these ap...
A useful mnemonic to remember the thoracic spinal levels at which the three major structures pass through the diaphragm is:
I ate (8) 10 eggs at 12
I ate (8): inferior vena cava at T8
10 eggs: (o)esophagus at T10
at 12: aorta at T12
Diaphragmatic eventration refers to an abnormal contour of the diaphragmatic dome. It typically affects only a segment of the hemidiaphragm, compared to paralysis/weakness where the entire hemidiaphragm is typically affected.
Diaphragmatic eventration is congenital in nature and due...
Diaphragmatic hernias are defined as either congenital or acquired defects in the diaphragm.
Demographics and aetiology
There are two main types of congenital diaphragmatic hernia (CDH)s which are uncommon yet distinct entities that usually occur on the left side (80%) of the diaph...
Diaphragmatic paralysis can be unilateral or bilateral.
Clinical features are highly variable according to underlying aetiological factor:
unilateral paralysis: asymptomatic in most of the patients as the other lung compensates
may have dyspnoea, headaches, fatigue, ins...
Diaphragmatic rupture often results from blunt abdominal trauma. The mechanism of injury is typically a motor-vehicle collision.
Given that the most common mechanism is motor vehicle collisions, it is perhaps unsurprising that young men are most frequently affected. The estimated ...
A small cardiothoracic ratio (CTR) as defined as <42%/0.42 when assessed on a PA chest radiograph, and can be due to number of entities:
adrenal insufficiency, e.g. Addison disease
asthmatic paroxysm ...
An anterosuperior mediastinal mass can be caused by neoplastic and non-neoplastic pathology. As their name suggests, they are confined to the anterior mediastinum, that portion of the mediastinum anterior to the pericardium and below the level of the clavicles.
The differential diagnosis for a...
Diffuse alveolar damage (DAD) is a common manifestation of drug-induced lung injury that results from necrosis of type II pneumocytes and alveolar endothelial cells.
Affected patients present with dyspnoea, cough, and occasionally fever. Diffusing capacity of the lung for...
Diffuse alveolar haemorrhage (DAH) is a subset of diffuse pulmonary haemorrhage when bleeding is diffuse and directly into the alveolar spaces. It can occur in a vast number of clinical situations and can be life threatening.
Blood tends to fill alveolar spaces as multiple sites.
Diffuse ground glass nodules can arise from many causes. These include:
atypical infections (especially in immunosuppressed patients) 1,3
pneumocystis jirovecii pneumonia
pulmonary herpes simplex infection
pulmonary respiratory syncytial viral infection
Diffuse idiopathic pulmonary neuroendocrine cell hyperplasia (DIPNECH) is an extremely rare pulmonary disorder where there is a proliferation of neuroendocrine cells within the lung. It is however recognised with increasing frequency.
There may be an increased female predilection ...
Diffuse panbronchiolitis (DPB) or Asian panbronchiolitis is an idiopathic progressive inflammatory small airway obstructive lung disease.
There is striking predilection in east Asia (e.g. Japan, Korea, China). It tends to present in middle aged (~ 30-60-year-old) adults, often non...
Diffuse pleural thickening refers to a morphological type of pleural thickening. It can occur from malignant as well as nonmalignant causes, which include:
diffuse pleural fibrosis / fibrothorax 6
asbestos related pleural disease: typically seen a continuous sheet of pleural thickening often i...
Diffuse pulmonary haemorrhage (DPH) is a subtype of pulmonary haemorrhage where bleeding into the lung is diffuse. If the bleeding is into the alveolar spaces this can be further subclassified as diffuse alveolar haemorrhage (DAH).
While the exact presentation can vary is...
Diffuse pulmonary lymphangiomatosis (DPL) is a rare condition characterised by diffuse proliferation of anastomosing lymphatic channels (lymphangiomas).
There is no recognised gender predilection. It typically manifests in children and young adults.
Diffuse pulmonary nodules are usually seen as multiple pulmonary nodular opacifications on a HRCT chest scan. They can signify disease processes affecting either the interstitium or the airspace. They can range from a few millimetres to up to 1 cm and when very small and numerous there can be so...
A number of differentials must be kept in mind while approaching diffuse pulmonary nodules. Interpretation is easier if nodules are the only abnormality.
These differentials can be narrowed down based on the several criteria:
Based on appearance
Diffuse pulmonary parenchymal amyloidosis is considered the least common form of pulmonary amyloidosis 6.
Unlike the nodular form, patients tend to be more symptomatic and often have symptoms of cough and shortness of breath. The most common presentation in this form ten...